摘要:

Twenty‐two genera representing sixty‐two species of Cunoniaceae andDavidsoniawere examined with respect to floral anatomy. Sepals are vascularized by three traces with the lateral traces of adjacent sepals united.Pancheriais unique for the family with species in which the sepals are vascularized by a single, undivided bundle. Petals, when present, and stamens, are uniformly one‐trace structures. A general tendency exists within the family for the principal floral bundles to unite in various ways, with fusions evident between calyx, corolla, and androecial vascular supplies. Carpel number ranges from two to five and the gynoecium is generally surrounded by a prominent disc. Gynoecia ofCeratopetalumandPulleaare “half‐inferior.” The number of ovules per carpel locule ranges from one to numerous. Ventral carpel sutures range from open to completely sealed at the level of placentation. Carpels of the apocarpous genusSpiraeanthemum(incl.Acsmithia)are vascularized by a dorsal bundle and either three or four bundles constituting the ovular and wing vasculation in the ventral position, a condition unlike other members of the family. Ovules are supplied by the median ventral bundle. More advanced bicarpellate gynoecia within the family are predominately vascularized by a dorsal and two ventral bundles although a variable number of additional lateral wall traces may be present. A major trend exists toward fusion of the ventral bundles of adjacent carpels in the ovary of both bicarpellate and multicarpellate plants. At the base of the styles the fused ventral strands separate and extend along with the dorsal carpellary bundles into styles of adjacent carpels. InPulleathe ventral bundles terminate within the ovules. The united ventral carpellary bundles inAphanopetalum, Gillbeea, andAistopetalumlie in the plane of the septa separating adjacent carpels. Ovules are vascularized by traces originating from the vascular cylinder at the base of the gynoecium or by traces branching from the ventral bundles. Ovular traces in each carpel are united, or remain as discrete bundles, prior to entering the placenta. Tannin and druses are common throughout all floral parts. Although floral anatomy generally supports the position of Cunoniaceae near Saxifragaceae and Davidsoniaceae, the evolutionary relationship of the Cunoniaceae to the Dilleniaceae is uncertain.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14068.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

The gametophyte ofTrichomanes pinnatumis filamentous save for its club‐shaped archegoniophores. Gametangial structure is consistent with that of related species. The apogamous embryo originates from the archegonial jacket and contiguous tissue such that there is no external indication of apogamy. The life cycle follows the Döpp‐Manton scheme. Specimens were studied which were homozygous for a paracentric inversion and these showed chromosomal bridges and associated fragments at meiosis‐I, thus confirming cytologically the occurrence of homoeologous pairing.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14069.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

The detailed ontogeny of postgenital fusions within the gynoecium ofCatharanthus roseuswas investigated. The basal margins of the young carpel primordia infold and fuse together to seal shut the loculi. Independently, the opposing distal tips of the two carpels also unite, with the fusion region subsequently developing into the stigma, style, and a small distal region of the compound ovary. The basal ovary regions of the two opposing carpels remain unfused, thus leaving the tip fusion spatially restricted. In the region of contact, cells with distinctively epidermal features progressively lose their epidermal character after their participation in the fusion. In the fused stigma these former epidermal cells redifferentiate into transmitting and secretory tissues; in the fused style these cells undergo a tremendous expansion in length while forming stylar transmitting tissue; but in the compound ovary region corresponding cells experience little expansion or redifferentiation. It is concluded that the loss of epidermal features or the occurrence of periclinal cell divisions in the epidermis is a definitive indication that cells have fused postgenitally. However, studies with the transmission electron microscope are necessary to detect the first indications of a postgenital fusion. The compound ovary region within the gynoecium ofC. roseusis a tissue appropriate for a high resolution ultrastructural study of the cytological events accompanying postgential tissue fusion because the fusion occurs quickly and little subsequent cell expansion takes place within this region.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14070.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Coralloid roots of cycads were found to originate endogenously from the pericycle of apogeotropic secondary roots or adventitious roots that have become exposed or nearly exposed to the soil surface. All mature coralloid roots are susceptible to infection by algal endophytes, which seem to enter from the soil through a break in the dermal layers.In the coralloid roots the algae inhabit intercellular spaces in a definite zone that arises from the protoderm, and in which the cells elongate radially following algal infection. The zone is completely surrounded by a persistent rootcap which is interpreted by most authors as a secondary cortex. The secondary cortex was shown to be derived from the rootcap in this investigation.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14071.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

The sclerophyllous evergreen shrub vegetation of southern California and central Chile is characterized by several examples of morphologically similar species. For each one out of a group of four Californian shrub species, four morphologically analogous sclerophyllous evergreens from Chile were chosen. In monthly intervals two‐year branchlets from these eight species were collected and their cambium activity was evaluated by means of a histological analysis. Similar shrub species from Chile and California show a surprisingly strong coincidence in their seasonal fluctuations of cambium activity regardless of their systematic position. This observation is interpreted to mean that convergence has taken place.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14072.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Spinules ofCarina generalispollen are initiated within a tridimensional network during the microspore tetrad period. The network is stained selectively with the hydrazide‐silver proteinate method of Thiéry following periodate oxidation and by phosphotungstic acid at lowpH, demonstrating the presence of polyanions. Protein is indicated as a component of the network by positive staining with PTA in acetone. These results suggest the presence of polysaccharides and proteins, possibly as mucopolysaccharides or glycoproteins. The network may be considered as a part of the glycocalyx because of its composition and association with the plasma membrane. Sporopollenin accumulates on the tridimensional network or in meshes of the net. The beaded fine structure of spinules resists the acetolysis mixture of Erdtman. Our results imply that the plasma membrane and its glycocalyx are part of the system which mediates genetic expression of exine form. The implication is compatible with formation of specific exines on all pollen grains of a plant and on aborted microspores, diminutive spores with depauperate chromosome complements, and enucleate bodies of cytoplasm resulting from meiotic abnormalities.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14073.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Leaf anatomy of 63 taxa is investigated to elucidate generic relationships amongBrachychaeta, Brintonia, Chrysoma, Euthamia, Gundlachia, Oligoneuron, Oreochrysum, Petradoria, andSolidago.All these genera have been included at one time or another withinSolidago. Aster ptarmicoidesis also studied because it hybridizes with some species ofSolidago(sens. str.). Qualitative and quantitative differences in mesophyll, storage parenchyma, secretory apparatus, bundle sheath extensions, and midvein structure allow rather precise grouping of the taxa.Brachychaeta, Brintonia, Oligoneuron, Oreochrysum, andAster ptarmicoidesshould be considered as constituents ofSolidago.They all have bundle sheath extensions and little or no water storage parenchyma. InSolidagosecretory cavities, when present, are shaped and positioned differently from those inEuthamia.The absence of bundle sheath extensions and various combinations of other anatomical features suggest thatChrysoma, Euthamia, Gundlachia, andPetradoriaare generically distinct from one another and fromSolidago.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14074.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Chromosome number determinations are reported for 101 collections distributed among 54 species of the North American Euphorbiaceae. First counts are presented for 44 species. When appropriate, systematic discussions regarding chromosomal information are included. Camera lucida drawings are published for previously undocumented chromosome reports.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14075.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Soybean plants(Glycine max‘Harasoy’) grown in horticultural perlite with a manganese‐deficient nutrient solution, developed typical deficiency symptoms of interveinal chlorosis and necrosis. A decrease in photosynthetic rate, dry leaf weight, leaf area, chlorophyll content, and chloroplast number was observed in plants displaying the deficiency. Transmission electron microscopy of manganese‐deficient leaf tissue revealed disorganization in the chloroplast lamellar network, nonhomogeneous distribution of the stroma, and a reduction in quantities of starch, which became increasingly more acute from nodes three to five in plants 28 days postgermination. The data suggest that manganese functions both as a requirement in the photosynthetic apparatus and as a structural component in the lamellar membrane.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14076.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Relative amounts of nuclear DNA were determined in root tip cells of seven species of Astereae:Aster hydrophilusGreene,A. oblongifoliusNutt.,A. ripariusH.B.K.,Machaeranthera boltoniae(Greene) Turner and Home,M. brevilingulata(Sch‐Bip.) Turner and Home,M. parvifloraGray, andM. tenuis(S. Wats.) Turner and Home. The results show thatA. hydrophilusandM. brevilingulata, with a chromosome number of n = 9, have less nuclear DNA than other closely related species which are either n = 4 or n = 5. Cytological analyses of meiosis in the intergeneric hybridM. parvifloraXA. hydrophilusshowed cells with two or more small chromosomes of the latter species pairing with single large chromosomes of the former. Pachytene cells of the hybridsM. parvifloraXA. hydrophilus, M. parvifloraXA. riparius, andM. boltoniaeXM. tenuisshowed some unpaired chromosome segments. The significance of these results to chromosome evolution in the tribe Astereae is discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb14077.x

出版商:Wiley    

年代:1975

数据来源: WILEY